The INotifyPropertyChanged interface is used to notify clients, typically binding clients, that a property value has changed.

For example, consider a Person object with a property called FirstName. To provide generic property-change notification, the Person type implements the INotifyPropertyChanged interface and raises a PropertyChanged event when FirstName is changed.

For change notification to occur in a binding between a bound client and a data source, your bound type should either:

The following code example demonstrates the how to implement the INotifyPropertyChanged interface. When you run this example, you will notice the bound DataGridView control reflects the change in the data source without requiring the binding to be reset.

If you use the CallerMemberName attribute, calls to the NotifyPropertyChanged method don't have to specify the property name as a string argument. For more information, see Caller Information (C# and Visual Basic).

Replace the code in your Form1 with the following code and then change the namespace to the name of your project. As an alternative, you can name your project with the namespace name below when you create it.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Runtime.CompilerServices;
using System.Windows.Forms;
// Either change the following namespace to the name of your project, // or name your project with the following name when you create it.namespace TestNotifyPropertyChangedCS
{
// This form demonstrates using a BindingSource to bind// a list to a DataGridView control. The list does not// raise change notifications. However the DemoCustomer type // in the list does.publicpartialclass Form1 : Form
{
// This button causes the value of a list element to be changed.private Button changeItemBtn = new Button();
// This DataGridView control displays the contents of the list.private DataGridView customersDataGridView = new DataGridView();
// This BindingSource binds the list to the DataGridView control.private BindingSource customersBindingSource = new BindingSource();
public Form1()
{
InitializeComponent();
// Set up the "Change Item" button.this.changeItemBtn.Text = "Change Item";
this.changeItemBtn.Dock = DockStyle.Bottom;
this.changeItemBtn.Click +=
new EventHandler(changeItemBtn_Click);
this.Controls.Add(this.changeItemBtn);
// Set up the DataGridView.
customersDataGridView.Dock = DockStyle.Top;
this.Controls.Add(customersDataGridView);
this.Size = new Size(400, 200);
}
privatevoid Form1_Load(object sender, EventArgs e)
{
// Create and populate the list of DemoCustomer objects// which will supply data to the DataGridView.
BindingList<DemoCustomer> customerList = new BindingList<DemoCustomer>();
customerList.Add(DemoCustomer.CreateNewCustomer());
customerList.Add(DemoCustomer.CreateNewCustomer());
customerList.Add(DemoCustomer.CreateNewCustomer());
// Bind the list to the BindingSource.this.customersBindingSource.DataSource = customerList;
// Attach the BindingSource to the DataGridView.this.customersDataGridView.DataSource =
this.customersBindingSource;
}
// Change the value of the CompanyName property for the first // item in the list when the "Change Item" button is clicked.void changeItemBtn_Click(object sender, EventArgs e)
{
// Get a reference to the list from the BindingSource.
BindingList<DemoCustomer> customerList =
this.customersBindingSource.DataSource as BindingList<DemoCustomer>;
// Change the value of the CompanyName property for the // first item in the list.
customerList[0].CustomerName = "Tailspin Toys";
customerList[0].PhoneNumber = "(708)555-0150";
}
}
// This is a simple customer class that // implements the IPropertyChange interface.publicclass DemoCustomer : INotifyPropertyChanged
{
// These fields hold the values for the public properties.private Guid idValue = Guid.NewGuid();
privatestring customerNameValue = String.Empty;
privatestring phoneNumberValue = String.Empty;
publicevent PropertyChangedEventHandler PropertyChanged;
// This method is called by the Set accessor of each property.// The CallerMemberName attribute that is applied to the optional propertyName// parameter causes the property name of the caller to be substituted as an argument.privatevoid NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
// The constructor is private to enforce the factory pattern.private DemoCustomer()
{
customerNameValue = "Customer";
phoneNumberValue = "(312)555-0100";
}
// This is the public factory method.publicstatic DemoCustomer CreateNewCustomer()
{
returnnew DemoCustomer();
}
// This property represents an ID, suitable// for use as a primary key in a database.public Guid ID
{
get
{
returnthis.idValue;
}
}
publicstring CustomerName
{
get
{
returnthis.customerNameValue;
}
set
{
if (value != this.customerNameValue)
{
this.customerNameValue = value;
NotifyPropertyChanged();
}
}
}
publicstring PhoneNumber
{
get
{
returnthis.phoneNumberValue;
}
set
{
if (value != this.phoneNumberValue)
{
this.phoneNumberValue = value;
NotifyPropertyChanged();
}
}
}
}
}